The present invention relates to projectiles for firing in a gun barrel, and in particular, to projectiles that have rotating parts to reduce projectile spin.
For most small arms weapon systems, that is, weapon systems of caliber 40 mm or less, the gun barrels are rifled to induce a high angular spin to projectiles exiting the muzzle. Projectiles requiring spin for aerodynamic stability are called spin-stabilized projectiles. For other projectile types that do not require a high angular spin (or types that experience degraded performance when spun, e.g., fin stabilized projectiles) a "slip device" is normally mounted on the projectile body to reduce or eliminate spin induced by the rifling. This rotating device usually consists of a rotating band that is free to rotate or slip around the projectile body, thereby permitting only axial projectile motion and not rotational motion during firing. This technique has been used successfully with large caliber ammunition and in some instances with small caliber ammunition.
A serious drawback with the foregoing technique is that the "slip device," which is usually composed of a polymeric type material, is exposed to the environment and is subject to possible damage. Rough handling by soldiers and exposure to machine oils are just a few possible situations that may damage the "slip device." This situation can lead to poor performance or failure of the ammunition if sufficient damage occur to the "slip device."
Accordingly, there is a need for an arrangement to reduce the spinning of a projectile to avoid performance degradation in a way that is relatively immune to damage from handling.